@Kronos
I see what you mean, I hadn't considered the CVision PPC and GRex.
I think its safe to say that any additional memory installed on a CPU slot accelerator could not be contiguous with the first 128Mb block, even if it is possible to make a card which supports it.
Presumably the CSPPC expansions must map either into the Zorro III space (if that's possible) or above 2Gb. I don't understand this enough to make any further comments.
Where's a hardware engineer when you need one

Robert